Add to all this the Vivacity, the Gayety which does alwayes more or less result from brisk Motion, whether it is caus’d by the spirits expanding themselves, or the Fibres dilating themselves to take in a greater quantity of the Spirits, it is hard to determine, and perhaps of no great consequence if we could; but that I may represent the Sense we may conceive of this, I think I have no reason to be asham’d to borrow for once more an Illustration from that Noble Beast, to which this Exercise I am treating of is owing; It is a known Case then, that if you take a Horse of the best Spirit, and of the best Keeping, provided he is not Vicious, as they call it; if you mount this Horse, and walk him or keep him to a pretty slow pace, you’ll find him quiet enough, but if you once put him on to a larger Pace, he can’t contain himself, but will grow troublesome, and press for a swifter Career, than perhaps his Rider would desire; which plainly shews, that there is something in the Animal Oeconomy, which _crescit eundo_, which gathers by Motion, and which can’t perhaps be made to display it self so well any other way; for this must not be thought to be wholly owing to high Feeding, but to the degree of the Motion; for the same Sprightliness or Courage will appear proportionally in any sort of Motion: And but a slow Motion in some Cases does not want its good Effects; those who are Judges of the Art of War, tell us that it is not best for a Body of Men to stand still and expect the Enemy, but to keep in Motion while they are drawing to the Battle; and in the time of a Siege, they make it a Rule, to remove their Men from one Post to another; that their Spirits may be kept up by their being in a continual Diversion. We are as subject to the Impressions of Motion, as to those of Sound and Harmony, and both are able sometimes to inspire a Flash of Courage into the Mind, that is not to be despis’d; and as one was of Use to drive away the Evil Spirit of Old, so the other may be of Service, to dispel the Hypochondriack Cloud, the desponding imaginations of Sick Persons; a Man may be able by this means to rouze himself, and shake off that _Incubus_ of the Brain, that lies brooding of Causeless Fears and Doubts, to the great hindrance of all his Endeavours after Health; it is no small matter for a Person to hope and believe that he shall do well, it is some Advance towards a Cure to have so much Courage, Ἤν φόβος καὶ δυθυμὶη, &c. _Si Metus & Tristitia multo tempopore perseverent, Melancholicum hoc ipsum_; As _Hippocrates_ observes in one of his _Aphorisms_ of his _fifth Section_, Fear and Sadness are sufficient to create a Distemper, and therefore may be very well thought to obstruct greatly the Cure of one; those Passions cause the Motion of the Heart, and the Beat of the _Artery_ to be weaker and consequently must proportionably lessen insensible Perspiration, which depends so much upon the Vigour of that Motion: We see a more than usual